Applying reticular synthesis to the design of Cu-based MOFs with mechanically interlocked linkers

The concept of“robust dynamics”describes the incorporation of mechanically interlocked molecules(MIMs)into metal-organic framework(MOF)materials such that large amplitude motions(e.g.,rotation or translation of a macrocycle)can occur inside the free volume pore of the MOF.To aid in the preparation of such materials,reticular synthesis was used herein to design rigid molecular building blocks with predetermined ordered structures starting from the well-known MOF NOTT-101.New linkers were synthesized that have a T-shape,based on a triphenylene tetra-carboxylate strut,and their incorporation into Cu(II)-based MOFs was investigated.The single-crystal structures of three new MOFs,UWCM-12(fof),β-UWCM-13(loz),UWCM-14(lil),with naked T-shaped linkers were determined;β-UWCM-13 is the first reported example of the loz topology.A fourth MOF,UWDM-14(lil)is analogous to UWCM-14(lil)but contains a[2]rotaxane linker.Variable-temperature,²H solid-state NMR was used to probe the dynamics of a 24-membered macrocycle threaded onto the MOF skeleton.     

中国建材企业“走出去”北京宣言

正建筑材料是显示人类文明文化的主要标志之一。中国建筑材料的历史悠久,为人类文明发展做出了巨大贡献。如今,中国建材行业正在践行"创新提升、超越引领"的发展战略,已经开始由产品"走出去"为主转向以资本"走出去"为主的国际化经营转型,以最新的建材产品和准备以最新的技术装备融入广泛的国际市场。参加"中国建材企业‘走出去’座谈会"的全体代表,就中国建材产品、技术、装备加快"走出去"步伐,为奠定中国建材工业创新提升、超越引领世界建材工业迈出新的征程形成共识。为此,     

基于性能的输电塔地震易损性分析

本文以某高压输电塔为研究对象,同时考虑了结构本身的随机性和地震作用的随机性,采用了非线性屈曲分析及动力响应分析对结构的抗震性能、地震反应进行了分析。在基于性能的分析框架下,通过蒙特卡罗数值模拟获得了输电塔的抗震能力曲线,并分析了其统计特性,计算得到结构的地震易损性曲线,为输电塔的抗震防灾规划提供风险评估的数据基础。     

Memristive Artificial Synapses for Neuromorphic Computing

Neuromorphic computing simulates the operation of biological brain function for information processing and can potentially solve the bottleneck of the von Neumann architecture.This computing is realized based on memristive hardware neural networks in which synaptic devices that mimic biological synapses of the brain are the primary units.Mimicking synaptic functions with these devices is critical in neuromorphic systems.In the last decade,electrical and optical signals have been incorporated into the synaptic devices and promoted the simulation of various synaptic functions.In this review,these devices are discussed by categorizing them into electrically stimulated,optically stimulated,and photoelectric synergetic synaptic devices based on stimulation of electrical and optical signals.The working mechanisms of the devices are analyzed in detail.This is followed by a discussion of the progress in mimicking synaptic functions.In addition,existing application scenarios of various synaptic devices are outlined.Furthermore,the performances and future development of the synaptic devices that could be significant for building efficient neuromorphic systems are prospected.     

AA7075高强铝合金热冲压流变行为本构模型对比研究

在热冲压过程中,AA7075高强铝合金板料经充分固溶后移入室温模具进行冲压成形并淬火。为表征AA7075铝合金在热冲压工艺中的变形行为,在温度200~480℃、应变速率0.01~10s-1范围内进行了高温拉伸试验。基于Arrhenius类型本构模型、Johnson-Cook模型以及Zerilli-Armstrong模型提出了多种修正本构模型,并应用实验所获流变曲线进行了拟合。提出的修正模型通过将模型参数表示为应变、应变速率及温度相关的多项式函数耦合了应变、应变速率及温度对流变应力的影响,并通过均方误差(MSE)以及相关系数R值对模型流变应力预测准确性进行了评价。结果表明,修正的Johnson-Cook模型能够更加准确的预测AA7075高温流变行为。     

Processing Research on Shaping Porous 316L Stainless Steel via SLS

The principles of selective laser sintering (SLS) were applied in this experiment .The influence of laser power, scan distance, scan speed and other processing parameters of fiber laser on the pore properties, elastic modulus, and micro morphology, etc were investigated in this paper. Tests were conducted on 316L stainless steel powder. The results showed that porous metal material that meets the requirements of porous bionic human bone material (porosity of 33.4%-37.8%, average pore radius of 94.2-178 μm, ...     

Message redundancy removal of multi-copy routing in delay tolerant MANET

This article puts forward a new scheme to control message redundancy efficiently in delay tolerant mobile Ad-hoc networks(MANET).The class of networks generally lacks end-to-end connectivity.In order to improve the efficiency that messages are delivered successfully,multiple message copies routing protocols are usually used,but the network load is increased due to a large number of message redundancies.In the study,by using counter method,every node adds an encounter counter based on epidemic routing scheme...     

用于激光器的电感储能发生器

研制了适用于激光器的电感储能发生器(GIES),并研究了它在高压混合气体中的放电和激光参数.研究表明,电感储能发生器可产生高压预脉冲并引起放电电流的突然增大,可在不同的混合气体中形成长时间的稳定放电,从而方便地控制和优化每一种气体混合物的预脉冲参数.在未知IES击穿电压和首次放电幅度下的参数时,电流尖峰会按因子1.5-...     

Monte Carlo study of spatial resolution of the scintillation camera

The aim of this study was to evaluate the influence of different entrance surface treatments of the scintillator on the intrinsic spatial resolution of a scintillation camera.The primary scintillation light reflection on the entrance surface of a scintillator may be affected by the optical coating of the entrance surface,resulting in either spatial resolution or system detection efficiency degradation.A Monte Carlo simulation model,based on Geant4 codes,was developed in order to study the scintillation ligh...     

Holding Pattern

Holding Pattern是Interboro事务所为MoMA PS12011年青年建筑师计划提交的获胜方案,它是为MoMA PS1在2011年6月19日开放的露天庭院而做的一个项目。为了设计Holding Pattern,Interboro向博物馆的邻居们调研了以下问题:有没有什么你们需要的东西我们可以设计,然后将之布置在这个庭院中展览并使用一个夏天,到秋季撤展的时候再捐赠给你们?Interboro询问了出租车公司、图书馆、高中、老年中心和日托中心、社区公园、邮局和很多其他位于纽约长岛的机构,